Patent Literature 1 (PTL 1) below discloses radio equipment configured to monitor the conditions of mechanical equipment within a combustible gas or explosive gas environment. This radio equipment is a radio sensor connected to a radio network where the radio sensor can transmit a detected physical parameter. The radio equipment includes a vibration sensor, a processor, a radio transmitter, a battery and a base portion where these constituent elements are mounted, as well as a cover portion attached to the base portion, configured to cover the equipment mounted on the base portion. The battery is fastened to a substrate supported on the base portion with a clamp. The processor and a radio communication device or the like are mounted on the substrate.